Egmond, J. van

Theoretical Philosophy

On the Empirical Equivalence of the Ether and Spacetime

In the introduction some initial appeal to an alternative to the General Theory of Relativity is presented. In this alternative, the role of a medium in absolute space, as opposed to a relative spacetime, is prominent. The main research question of this thesis then becomes whether this alternative can be superior to the General Theory of Relativity. Answering this question is especially difficult in the case where there are no empirical arguments in favor of one or the other. This thesis can be split in the three tasks that naturally follow: establish an evaluation method, show that the alternative is empirically equivalent to the General Theory of Relativity and evaluate the two theories.

In the first chapter an evaluation method is derived especially for this particular kind of case of empirical equivalence. This evaluation method is constructed during a discussion of paradigm shifts in cosmological theories; in particular geocentric and heliocentric models. In the second chapter it is shown that a conceptual reconstruction of Lorentz’ and Poincaré’s ether theory is empirically equivalent to the Special Theory of Relativity. Lorentz’ and Poincaré’s ether theory is then used as a basis for the alternative gravitational theory. The third chapter discusses the General Theory of Relativity and its empirical validations, which shows the requirements for gaining empirical equivalence with that theory. The fourth chapter extensively elaborates on the ether theory for gravity. Most importantly, it is shown that it is possible to gain empirical equivalence with the General Theory of Relativity. The final chapter evaluates both theories according to the evaluation method as constructed in the first chapter. The main conclusion is that the ether theory for gravity cannot yet be discarded. As it does especially well outside the realm of gravity, it still has the potential to become a superior theory to the General Relativity.